1. Field of the Invention
The present invention relates to a tire inflation pressure detecting device. In particular, the present invention relates to a tire inflation pressure detecting device having a layout capable of improving the reception of a condition regarding the result of a tire inflation pressure detection.
2. Description of Background Art
A tire inflation pressure detecting device is known that regularly measures the inflation pressures of tires and enables a checking of the inflation pressures of the respective tires from an operator's seat. Japanese Patent Application Publication No. 2006-240410 proposes a tire inflation pressure detecting system for a two-wheeled vehicle wherein tire inflation pressure sensors are respectively attached to front and rear wheels each include a transmitting circuit and by using the transmitting circuits, the tire inflation pressure sensors transmit signals indicating tire inflation pressures detected by the respective tire inflation pressure sensors. The signals are received by a first tuner and a second tuner which are provided in the front and rear of a vehicle body, respectively. In this system, the first and second tuners are provided to the front and rear of an engine, that is, in a widthwise central portion of the vehicle body.
As proposed in Japanese Patent Application Publication No. 2007-269202, a device is disclosed which has a controller system arranged under a rider's seat for detecting the presence or absence of a rider and a loading status of a load on the basis of inflation pressures. The controller system includes an antenna unit that receives the inflation pressure signals of tires.
As described above, in a conventional tire inflation pressure detecting system or device for a two-wheeled vehicle, while sensors and transmitters for tire inflation pressure detection are attached to rims of tire wheels, each of the tuners or the antenna unit is provided in a widthwise central portion of a vehicle body.
More specifically, a transmitter and a receiver for a tire inflation pressure signal are both located in the widthwise central portion of the vehicle body, and arranged substantially in a straight line along a front-rear direction of the vehicle body. Consequently, there are constituent elements of the vehicle such as an engine, a suspension mechanism and a muffler between the transmitter and the receiver. Thus, the reception status of radio waves transmitted from the transmitter sometimes is decreased.
On the other hand, in the device disclosed in Japanese Patent Application Publication No. 2007-269202, tuners, more specifically receivers, are arranged in vicinities of transmitters attached to the front and rear wheels. Thus, good reception conditions can be expected. However, in this device, plural receivers are necessary. Therefore, there have been problems wherein arrangement spaces for the receivers are respectively required. Thus, the interconnections become complex.